Abstract: A heat exchanger includes a plurality of longitudinally-extending first channels and a plurality of second channels fluidly isolated from the plurality of first channels. Each first channels includes a plurality of spiraling internal fins and a plurality of external fins. The internal fins extend from and are integrally formed with the internal walls of the first channel. The external fins connect extend from and are integrally formed with the external walls of the first channels, connecting channels together. The plurality of second channels is defined in part by external walls of the plurality of first channels and the plurality of external fins.

Abstract: A heat exchanger having: front and aft ends; heat exchanger cores in an annular loop that define circumferential gaps between adjacent pairs of the cores, the cores, individually or as axially aligned sets, extend from the front to aft ends and have facing inlet sides and circumferentially facing outlet sides configured such that the inlet sides and the outlet sides from the adjacent pairs of the cores face into the same circumferential gaps; and core guide vanes disposed in the circumferential gaps, the core guide vanes have an aft portion that extends from the front end to the aft end of the heat exchanger, wherein: at the front end the heat exchanger, the core guide vanes are closer to the outlet side of the cores; and at the aft end the heat exchanger, the core guide vanes are closer to the inlet sides of the cores.

Abstract: A heat exchanger having: an inlet header having inlet tubes stacked against the first side of the heat exchanger; an outlet header having outlet tubes stacked against the second side of the heat exchanger, first inlet and outlet tubes have a same length as each other, second inlet and outlet tubes have the same length as each other and are longer than the first inlet and outlet tubes, and third inlet and outlet tubes have a same length as each other and are longer than the second inlet and outlet tubes; core channels extend from the first side to the second side of the heat exchanger, the core channels connect the inlet tubes to the outlet tubes such that: the first inlet tube and third outlet tube are connected; the second inlet tube and second outlet tube are connected; and the third inlet tube and first outlet tube are connected.

Abstract: Cooling systems include a cold sink having a number of heat load cooling paths and a heat load associated with each cooling path. An inlet is configured to supply a cooling fluid into the cold sink and an outlet is configured to receive the cooling fluid after passing through the plurality of heat load cooling paths of the cold sink. A pressure regulating element is arranged along each cooling path, each pressure regulating element arranged between the inlet and the heat load along each cooling path and configured to cause a pressure drop in the cooling fluid prior to passing the cooling fluid to each heat load. The pressure drop caused by each pressure regulating element is the same and is a pressure drop greater than a maximum pressure drop across each heat load of a system without such pressure regulating elements.

Abstract: Cooling systems include a cold sink thermally coupled to a heat load, a separator configured to separate liquid and vapor portions of a working fluid, and a cooling cycle having a vapor loop and a liquid loop, the cooling cycle having the working fluid configured to pass through both the vapor loop and the liquid loop. The vapor loop includes the separator, a compressor, a condenser, and a valve. A vapor form of the working fluid flows from the separator into the compressor, and the working fluid then flows to the condenser, and then through the valve, and returned to the separator. The liquid loop includes the cold sink, the separator, and a pump. A liquid form of the working fluid flows from the separator into the pump and the working fluid is increased in pressure and supplied to the cold sink and then returned to the separator.

Abstract: A heat exchanger includes a plurality of longitudinally-extending first channels and a plurality of second channels fluidly isolated from the plurality of first channels. Each first channels includes a plurality of spiraling internal fins and a plurality of external fins. The internal fins extend from and are integrally formed with the internal walls of the first channel. The external fins connect extend from and are integrally formed with the external walls of the first channels, connecting channels together. The plurality of second channels is defined in part by external walls of the plurality of first channels and the plurality of external fins.

Abstract: A heat exchanger includes a plurality of longitudinally-extending first channels and a plurality of second channels fluidly isolated from the plurality of first channels. Each first channel includes a plurality of internal fins and a plurality of external fins. The internal fins extend from and are integrally formed with the internal walls of the first channel. The external fins connect adjacent first channels. The plurality of second channels is defined by external walls of the plurality of first channels and the plurality of external fins.

Abstract: Aircraft engines and methods of operation include a core assembly having a compressor section, a burner section, and a turbine section arranged along a shaft, with a core flow path through the turbine engine such that exhaust from the burner section passes through the turbine section. A core condenser is arranged downstream of the turbine section of the core assembly along the core flow path, the core condenser being configured to condense water from the core flow path. A refrigeration system is operably coupled to the core condenser and configured to direct a cold stream flow path into thermal interaction with the core flow path at the core condenser and configured to control a delta temperature at which heat exchange occurs between the core flow path and the cold stream flow path.

Abstract: Aircraft engines include a turbine engine comprising a compressor section, a burner section, and a turbine section arranged along a shaft, with a core flow path through the turbine engine such that exhaust from the burner section passes through the turbine section, a condensing assembly arranged downstream of the turbine section of the turbine engine along the core flow path, and an exhaust compressor arranged downstream of the condensing assembly along the core flow path. The condensing assembly is configured to reduce a mass flow of the exhaust compressor by condensing water vapor from the core flow and removing liquid water from the core flow.

Abstract: Aircraft engines include a turbine engine comprising a compressor section, a burner section, and a turbine section arranged along a shaft, with a core flow path through the turbine engine such that exhaust from the burner section passes through the turbine section, a condensing assembly arranged downstream of the turbine section of the turbine engine along the core flow path, and an exhaust compressor arranged downstream of the condensing assembly along the core flow path. The condensing assembly is configured to reduce a mass flow of the exhaust compressor by condensing water vapor from the core flow and removing liquid water from the core flow.

Abstract: Aircraft engines include a burner section and a turbine section arranged along a shaft, wherein an exhaust from the burner section is directed through the turbine section to drive rotation of the turbine section and a core flow path passes through the burner section and then the turbine section. A condenser assembly is arranged downstream of the turbine section along the core flow path. A cryogenic fuel source is configured to supply fuel to the burner section along a fuel line passing through the condenser assembly and the fuel within the fuel line is configured to pick up heat from the exhaust from the burner section and condense water therefrom.